Method and apparatus for straightening arc-type continuous casting



United States Patent [72] Inventor Hans G. Baumann Duisburg, Germany [21] Appl. No. 683,589

[22] Filed Nov. 16, 1967 [45] Patented Dec. 1, 1970 [7 3] Assignee Demag Aktiengesellschaft Duisburg, Germany [32] Priority Jan. 18, 1967 [3 3 Germany [31] No. B52038 [54] METHOD AND APPARATUS FOR STRAIGHTENING ARC-TYPE CONTINUOUS I Primary Examiner-J. Spencer Overholser Assistant Examiner-R. Spencer Annear Attorney-McGlew and Toren ABSTRACT: An apparatus for straightening a casting in an arc-type continuous casting plant is formed of a number of serially positioned, horizontally arranged rolls. In the direction of its path of travel, the casting first passes between a pair of vertically aligned rolls at the point where the straightening process commences. This first pair of rollers drive the casting over a rigid support roll while two horizontally spaced rolls are positioned in contact with the upper surface of the casting. 1n the final straightening operation, the casting passes between two pair of withdrawing and straightening rolls. Each of these straightening and withdrawing rolls is individually driven and all of the rolls exerting a downward pressure on the upper surface ofa casting are individually adjustable.

METHOD AND APPARATUS FOR STRAIGHTENING ARC-TYPE CONTINUOUS CASTING SUMMARY OF THE INVENTION The present invention is directed to withdrawing and straightening apparatus for an arc-type continuous casting plant, and more particularly, to an arrangement wherein the casting is passed horizontally through withdrawing and straightening rolls in which the upper rolls are individually adjustable for selectively applying pressure to the casting and, further, the withdrawing rolls are individually driven.

Arc-type continuous casting plants are designed for careful handling of the curved castings as they are conveyed through the straightening apparatus because the core of the casting has a liquid or pasty consistency while its shell is in the range of the hot-working temperature. Previously, the withdrawing and straightening operation has been performed employing special forms of individually driven feed rolls. Accordingly, it is also possible in transporting the curved casting to adjust for the resistances provided by the mold and the supporting and guide means between the mold and the straightening apparatus. However, this does not solve the problem when the rolls located beyond the curved portion of the casting take over the task of withdrawing or driving the casting through the straightening apparatus.

Coordinating the straightening and transporting forces which act on the casting represents a special problem. Due to the condition of the casting, having only been withdrawn from the mold, the use of strong forces in working the casting would tend to crush it. Casting shells which are too roughly handled develop cracks and frequently result in nonuniform areas in the finished casting. These defective areas in either the internal or external portions of the casting must be avoided in order to obtain a usable end product. Accordingly, the present invention is directed to limiting the pressure applied to the casting shell as it passes through the straightening apparatus. In another previously known arrangement, the top rolls have been employed as driven rolls so that the frictional force exerted between the casting and the bottom rolls is determined by the weight of the casting section resting on the lower roll. Though this arrangement afforded relief from excessive pressures on the exterior of the casting, by employing the present invention, it is possible to regulate both the driving or withdrawing and the straightening forces independently of the weight of the casting.

Accordingly, the primary object of the invention is to provide a withdrawing and straightening apparatus for arc-type castings without exerting compressive forces on the casting which tend to damage either its exterior or interior structure.

Another object of theinvention is to provide individually driven rolls for the passage of the casting through the straightening operation.

Still, another object of the invention is to utilize adjustable LII upper rolls for individually limiting the amount of force or pressure exerted on the casting as it is processed through the straightening operation.

Therefore, in the present invention, the combination withdrawing and straightening rolls are arranged in pairs, however, the rolls are individually driven and the upper roll of each pair is adjustable for limiting the amount of pressure exerted on the casting. The basic concept of the invention is to arrange the upper rolls in the straightening apparatus to afford a bearing pressure on the casting sufficient to straighten it from its arc-type configuration, but not to otherwise injure the interior or exterior structure of the casting. Therefore, the upper rolls provide a pressure sufficient to overcome the tendency of the casting to retain its curved configuration but insufficient to cause any damage or crushing action in the castmg.

Initially, the individual adjustment of the pressure is provided at the point where the casting begins its transition from a curved to a straight or horizontal member. As the casting travels through the straightening apparatus, it is possible to apply greater adjusting forces as the casting is cooled and acquires a thicker shell, or a shell less vulnerable to extend pressures. As the casting solidifies during the straightening operation, the bearing pressure exerted by the upper rolls may be increased so that sufficient pressure is exerted on the casting to sufficiently or completely straighten it.

To improve the straightening operation, straightening rolls, which do not drive the casting, may be positioned intermediate the driven straightening rolls. These additional rolls include a rigid straightening roll located below the casting and adjustable straightening rolls contacting its upper surface. With these rolls, a rigid support is provided for the casting during ,a part of its path of travel in the straightening operation. Further if any stretching of the casting tends to occur, it can be readily balanced by varying the rotational speeds of the bottom driving rolls. In the arrangement described, a considerable advantage is attained in employing individually adjustable upper rolls which permit an increase in the bearing pressure applied to the rolls in a step-by-step manner directly related to the condition of the casting as it proceeds through the straightening operation.

The various features of novelty which characterize the invention are pointed out with particularity in the claims annexed to and forming a part of this specification. For a better understanding of the invention, its operating advantages and specific objects attained by its use, reference should be had to the accompanying drawings and descriptive matter in which there is illustrated and described a preferred embodiment of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS In the Drawings:

The drawing contains a schematic illustration of a curved casting passing horizontally through a withdrawing and straightening apparatus embodying the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS In the drawing, a mold l of the oscillating curved or straight-type is shown forming a continuous casting 2 which is shaped into a curved or arc-type configuration 2a by supporting or guide means (not shown). At the point 3, which represents the starting point of the straightening operation, the casting has a tendency to retain its curved shape 20 due to its cross-sectional form and size, and other of its properties including the materials from which it is formed.

In its horizontal orientation, the casting 2 rests on a number of individually driven lower rolls 4, 5 and 6 which form a part of the straightening apparatus and also of the withdrawing or driving apparatus for transporting the casting. Positioned between rolls 4 and 5, is an additional rigid bottom roll 7 which does not form a part of the driving system for the casting but combines with the rolls, 4, 5 and 6 to support the castmg.

Disposed above the casting, at the point 3, is a horizontally arranged individually driven upper roll 8 which forms a part of the withdrawing system for removing the casting from the mold and passing it through the straightening operation. The roll 8 is alined above the lower individually driven roll 4. Spaced along the path of travel of the casting from point 3 are two horizontally arranged and individually driven upper rolls 9 and 10 which form a part of the straightening apparatus for the casting. Located between the rolls 8 and 9 are a pair of straightening rolls 11 and 12, like the roll 7 these rolls do not form a part of the driving or transporting system for the casting. The rolls l1 and 12 are horizontally spaced, on either side, from the lower roll 7. It will be noted in the drawing that the pairs of rolls 4-8, 5-9, and 6-10 are illustrated with a circle having two opposite quadrants shown in black for indicating that each roll is individually driven. The rolls l1 and 12 which precede the rolls 5, 6 in the path of travel of the casting form a prestraightening operation on the casting.

All of the rolls contacting the upper surface of the casting, that is, rolls, 8, l1, l2, 9 and 10 as they appear in the drawing, are provided with piston drives 13 whereby each of the rolls is individually adjustable for reaction with the upper surface of the casting. Though the means for adjustable supporting the .upper rolls is shown as a piston drive 13, it will be appreciated that other means can also be used such as mechanical spindle drives. 7

In the present invention as the casting 2 passes point 3 and travels horizontally between the different sets of rolls the individual adjustment of the upper rolls assures the proper adjustment of the bearing pressure of the upper rolls on the surface of the casting as it cools in its passage through the straightening zone. Because of this individual adjustment, the casting can be carefully handled as it is straightened and any problems connected with defects in its surface due to rough handling are avoided. Further, because of this manner of handling, it can be assumed that the internal structurewill be homogeneous.

While a specific embodiment of the invention has been shown and described in detail to illustrate the application of the inventive principles, it will be understood that the invention may be embodied otherwise without departing from such principles.

lelaim:

1. Apparatus for straightening an arc-type casting in the course of its path of travel from its mold in a continuous casting plant, comprising a first pair of vertically spaced rolls located at the starting point in the transition of the casting from a curved to a straight configuration and arranged for the casting to pass between said rolls, each of the rolls in said first pair being individually driven and one of the rolls being arranged for adjustably applying pressure to the surface of the casting, and two further pairs of vertically spaced rolls spaced from said first pair of rolls in the direction of travel of the cast- I ing and arranged to straighten the casting, each said further pair of rolls arranged for the casting to pass therebetween, each of the rolls in said two further pairs of rolls being individually driven and one of the rolls in each of said two further pairs of rolls being arranged for adjustabiy applying pressure to the casting, and a plurality of rolls disposed between said first pair of rolls and said further pair of rolls for supporting the casting in its path of travel therebetween and for assisting in the straightening operation.

2. Apparatus for straighteningian arc-type casting, as set forth in claim 1, wherein the casting is in the horizontal position as it 'passes between said first pair of rolls and said two further pairs of rolls, said plurality of rolls comprises a pair of horizontally spaced rolls positioned between said first pair of rolls and said two further pairs of rolls and arranged to contact the upper surface of the casting and a rigid roll arranged to contact the lower surface of the casting at a position between the locations at which said pair of horizontally spaced rolls contact the casting, said pair of horizontally spaced rolls contacting the upper surface of the casting arranged for adjustably applying pressure to the upper surface of said casting.

3. A method of straightening continuous castings formed in an arc-type continuous casting plant comprising, passing an arc-type casting horizontally through a straightening station while serially performing the steps of adjustably applying pressure to the upper surface of the casting while supporting and driving the casting at its upper and lower surfaces for initiating the straightening action at the transition point from an arctype to a straight configuration of the casting, passing the casting over a rigid support surface while individually adjustably applying pressure to the upper surface of the casting at least at two spaced locations in the direction of travel of the casting from the transition point and increasing the pressure applied as compared to the pressure applied at the transition point, and then individually adjustably applying pressure to the upper surface of the casting while supporting and driving the casting at least at two spaced locations in the direction of travel of the casting from the transition point after its passa e over the rigld support and increasing the pressure previous y action yet is insufficient for causing any damage or crushing action in the casting. 

